Thermoelectric properties of Gd, Y co-doped Ca3Co4O9+δ

Effects of Eu and Fe co-doping on thermoelectric properties of misfit-layered Ca3Co4O9+δ

“…Thus, the electrical resistivity increases. Similar results were also reported by some groups [11][12][13][14][15][16]28]. As for the x = 0.1 and y = 0.1 sample, its semiconducting-like character is clear at measured temperature.…”

“…Eu, Y, Lu and Dy etc.) can enhance the thermopoower, but also increase the resistivity [11][12][13][14][15][16]. In contrast, doping in Co-site is more complicated due to the intrinsic feature of multiple oxidation states of the transition metals as dopants as well as the presence of two nonequivalent Co sites in the [Ca 2 CoO 3 ] and [CoO 2 ] subsystems [7,9,[17][18][19].…”

Effect of Ag additions on the Bi_1.6Pb_0.4Sr₂Co_1.8O_x thermoelectric properties

“…Other possibilities arising from the crystallographic structure of these materials are the cationic substitutions in the RS layer, which can change the misfit relationship between the two layers and, as a consequence, modifying the values of the thermopower [7]. From this point of view, it is clear that this kind of substitutions can be useful in order to improve thermoelectric performances of ceramic materials [19], as it is reported for the substitution of Gd and Y for Ca [23], or Pb for Bi [24][25][26]. Moreover, metallic Ag additions have also shown to improve, in an important manner, the mechanical and electric properties of this system [27] and other similar materials [28] which nearly do not react with Ag, as it has been found in some phase diagram studies [29].…”

Enhancement of Ca 3 Co 4 O 9 thermoelectric properties by Cr for Co substitution

“…Furthermore, it has also been found that the Seebeck coefficient values are governed by the incommensurability ratio and/or the charge of the RS block layer between the CoO 2 ones [9]. This is the basis for the modification of thermoelectric properties of a given material via chemical substitutions, as Gd and Y or Sb for Ca in Ca 3 Co 4 O 9 [12,13] [16].…”